This specification generally relates to a method and apparatus of electrostimulation of body tissue, including methods of transcranial electrostimulation. For example, plastic changes in brain function can be safely induced in humans by low-intensity electrical stimulation through scalp electrodes. Such electrical stimulation is known as transcranial electrostimulation (TES). These changes can be potentially used for therapeutic or performance enhancing applications. Currently available devices are rudimentary in the sense that they do not target brain modulation and do not apply insights from biophysical studies to functionally target brain function. Moreover, current methods of TES targeting require costly and time consuming computations in order to alter treatment methods.